Process of making commercially-pure iron alloys



I 50 be carried Patented Apr. 3, 1928.

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UNITED STATES PATENT cmcr.

LEO r. nnmnnrz AND .rom: 11., mun, or unmmrown, onro, lnssrenons 'ro m maroon norrmemrm'. conrm, or umnrnrown, 9310, a conrom'rron or OHIO mnawag. V

ingot iron as produced in the open heart furnace.

The-Carnahan process of manuiacture of ingot iron, that is to say, a highlypurified. produced in a manner analo ous to product that of steel, taught that with a big to o tain ahighly refined iron product in molten condition, provided certain 'outside limits were established for the analysis of the final product, andprovided .a de-gasification with aluminum or some other like acting metal was thoroughly made. De-gasificationin the ladle was the preferred method em- I loyed byCarnahan, and in such alloysas 6 spoke of, the de-ga'sification was called for, to be completed after the alloying'metal gad been, incorporated with the pure iron ase. 7 In the production of a number of the alloys of iron, particularly chromium alloys, it is advantageous to have the. final product vely low in carbon to facilitate cold working an forming. This is also true of alloys" with nickel, Vanadium, cobalt, molybdenum, titanium and the like. j

Referring more particularly to the pro- I .duction of an alloyuon a base of cia;lly pure iron w 'ch has been produced economically in the open hearth furnace, the danger-point in the operation lies in-the tendency of irons so produced having an ex: cessive oxygen and gas content generally due to the long continued heating and high .teme peratures. the production 40 other alloys of pure iron in which the added metal is itself more readily burned up than iron, the loss from burning of the alloying metal is not only a financial loss but results in a non-uniform product being produced as it. is difiicult to predetermine the amountwhich be consumed. a r It may be generally stated as the ob'ct of our invention to provide arocess w ereby the production of alloys 0 pure iron may particularly chromium alloys, with the r t of producing a material regularly and uniformly rollable' into sheets,

strips, and othershapes, and soft enough for subsequent formm operation such as stamping, drawing and e like.

' Application area October 4',

tent isjextrem'ely low. a One of the obj ts of is to provide for the'use of molten ingot iron,

ered furnace, and long sustained at- 'gh" 0 tem eratures, it was possible with regularity used at the present time,

' the'same iron production.

commer- 2c caomam alloys and.

' carbon- :rnocnss or Max ne commnnomii-ruanmon armors.

we no. 666,611. r

Sue alloys will have corrosion resistant; properties which are -commonly a termed isdirected-toward the production 0 rustle'ss'or stainless, and our rooess i less'iron products in whichfthe carbon con eo our invention also,

having'very low. impuri v range, and pro.-.' duc ed in the-open hearth furnace, in such a way that a portion of the production of-=such ingot iron may be diverted into alloy making, and'therbalance used in the production ofthe pure ingots. There'is a great quantity? of this open hearth ingot iron produced and v and-it is of essen tial commercial importance to provide a I process. in-which a portion of the molten metal obtainedby 'pping from the ogen hearth furnace can be diverted into a oy {5- making, without interfering with the use of 7 heat of metal in the. usual ingot 4 So far as we are advised, all very low carbonbase iron alloys, particularly with chromium have been produced in what may betermed a single-operation, utilizing the electric furnace, and while our process has 'points of value and V novelty over such meth odsof production in the past, itisto our mind more important from the point of view of the possibility ofusing-thereby a portion of the product of the open hearth furnace, thereby cutting down the cost of production, and eliminating the equipment cost used m the productionfof alloys on apure iron base. We describe in detail the proce m using chromium, or chromium sihcon alloy,-

tihe production of a very mild alloy materla a v 'Molten commercially pure iron from an I open hearth furnace or other furnace is oured into an-electric furnace which should epreheated to high temperature; re--' ducmg slag is made on the bath with lime moand ferro silicon or aluminum, and the metal is thoroughly de-oxidized or killed in the a furnace with ferro" silicon, aluminnmp other (ls-oxidizer. A calcium carbide slag may be made'if care is taken to prevent the powder. from getting into contact with the metal. The process of the invention may be-carj ried out all commercially pure iron an oxidizr10 in one electric furnaceby makl in g/slag until the desired purity is reached,

then removing the oxidizin slag and'mak ing a reducing give any desired chromium content up to 20% chromium. It is immaterial whether the chromium addition be made cold, preheated, or molten, except that the hotter is the addition the shorter will be the time for melting and thorough mixing. It is during this period that great care must be taken to prevent the absorption of carbon by the bath.

It should be noted ,pf our process that it varies from Carnahan s ideas and teachings in that thealloypis made after the in ot iron has been dc-oxidized 'or' de-gasitied, or killed, and while the reducing slag is on the surface of the bath. This results in the safety of the remainder of the process and avoids the expensive treatments hitherto advanced" in the production of low carbon alkilled, verylow carbon chromium or ferro chromium-1s added in necessary amounts to loys with materials Which will so actas to i 're-carburize the bath as well as idissipate themselves. It also permits of using the ingot iron material of high purityl .range' by tapping it direct from open hearth furnace. Having thus described our invention, ,what we claim as new and desire to se'cure by'Lette'rs Patent, is

The process for production of alloys of low carbon content which consists in forming a bath of molten iron having very low carbon and verylow metalloid content undr oxidizing conditions, said molten iron while purified and molten but without degasification being located in an electric furnace, degasifying the molten iron in the electric furnace, in such a way as to -kill the iron, and without alloying the iron forming a reducin slag on the surface of the killed iron, an

while maintaining the heat in the electric furnace adding a substantially carbon tree "alloying metal.

:-- LEO F. REINARTZ.

JOHN H. NEAD.- 

